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Spring-driven high speed valve for massive gas injection in tokamaks
M Dibon1, K Mank1, G Pautasso1
1Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
The Review of Scientific Instruments
|April 5, 2017
Summary
A novel high-speed gas valve for tokamak disruption mitigation was developed. This robust, spring-driven valve operates within the vacuum vessel, enabling rapid gas injection for plasma stability.
Area of Science:
- Fusion Energy Research
- Plasma Physics
- Engineering
Background:
- Tokamak devices require effective disruption mitigation strategies.
- In-vessel gas injection minimizes gas cloud dispersion and flight time.
- Harsh environments within tokamak vessels demand robust valve mechanisms.
Purpose of the Study:
- To develop and characterize a new high-speed gas valve for disruption mitigation.
- To ensure rapid and localized gas injection into the ASDEX Upgrade tokamak.
- To validate the valve's performance under operational conditions.
Main Methods:
- Design and implementation of a spring-driven gas valve with an internal reservoir.
- Utilizing analytical and numerical methods to determine gas flow rate and velocity.
- Experimental characterization of valve opening time, gas velocity, and cloud expansion.
Main Results:
- The valve opens within 1.5 ms, achieving a peak flow rate of 72 kPam³/s after 1 ms.
- Maximum gas velocity of approximately 560 m/s is reached 0.6 ms post-actuation.
- The gas cloud exhibits a pear shape with a 49° opening angle.
Conclusions:
- The developed high-speed gas valve is suitable for in-vessel disruption mitigation in tokamaks.
- The valve's rapid response and controlled injection enhance plasma stability.
- The robust spring-driven design ensures reliable operation in challenging magnetic environments.